CHAPTER V. 



THE VENOMS. 



General Nature of Venoms. — The venoms are 

 more or less toxic products secreted by certain 

 reptiles, batrachians, and fish; by a large number 

 of invertebrates; by arachnids, apids, scorpionids, 

 araneids, and a large number of other insects. 



The venoms are toxic principles very closely 

 allied to the microbial toxins; like the latter, they 

 form two classes, the one alkaloidal, the other 

 proteid, possessing a true diastatic character. 

 They closely resemble the microbial toxins, more- 

 over, by the fact that they are capable of being 

 transformed into vaccins by attenuation of their 

 virulence, by the action of heat or chemical re- 

 agents, and of leading to habituation of use and 

 the conference of immunity.* Moreover, like the 

 various viruses, the serum of immunized animals 

 is antivenomous, so that if injected into the veins 

 or beneath the skin of non-immunized animals, the 



* Annal. de I'lmtit. Pasteur, viii, p. 281; Journ. of Physiol., 

 VIII, p. 203; and Soc. de Biol., 1894, p. iii. 



8S 



